Since I'm looking for some new boots as well, I thought I'd bring this back to the top.

Folks had mentioned they felt some of the Simms boots were to heavy.
I got this email from Simms today regarding the two model of boots I'm considering.
The Stremtread soles really add some weight, nearly one lb to the Headwater boots. I've got size 14 dogs and knee issues, so the heavy Guide boot option is out for me.

The Headwater Boot in felt is our lightest boot, weighing approximately 35oz (1 pair in a size 10).
The Headwaters Boot with the Streamtread sole weighs approximately 49.6oz (also for 1 pair in a size 10).

The Guide Boot in felt weighs in at approximately 56oz (1 pair, size 10).
The Guide Boot with the Stremtread sole weighs approximately 65.8oz (1 pair, size 10).